The present invention relates generally to an image forming machine and, more particularly, to an integrated adjustable core support and medium guide device adapted to be incorporated into a printer for properly holding medium rolls having different core diameters and for better aligning medium strips of the medium rolls moving from the core support to the medium guide of the integrated device.
Many conventional printers have certain medium holding mechanisms for supporting media mounted thereon. Typically, each of the media includes a medium strip wound on a support core forming a medium roll to be mounted on the medium holding mechanism of a conventional printer. The medium strip may be formed by a label strip, which includes a plurality of labels attached to a protective backing strip, or it may simply be formed by a paper strip. The protective backing of the label strip normally has a glossy surface attached to an adhesive surface of each label so that the labels could be easily peeled off from the protective backing. Each label also has a printable surface located opposite its adhesive surface.
Different conventional printers may have different kinds of medium holding mechanisms designed to fit their particular purposes. Ordinarily, the support core of the medium roll is tubular-shaped. The tubular support core could be made of plastic, cardboard, or any other materials that are suitable to hold the medium strip for mounting on the medium holding mechanism of the printer. The support core has an inner diameter and an outer surface where the medium strip is wrapped thereon. There are many different sizes of media used in the market for various business purposes. Thus, sizes of the support cores, e.g., the diameters and/or the lengths of the cylindrical support tubes,of the medium rolls have to be: accordingly varied in order to support different-sized medium strips. As a result, many commercially available medium rolls have different sizes of the inner diameters of their respective support cores.
As mentioned, commercially available medium rolls often come with different sizes. Therefore, medium holding mechanisms of most conventional printers have incorporated certain adjusting features to cope with the different-sized core diameters of the medium rolls. Typically, the medium holding mechanism of a conventional printer has a pair of support ears respectively positioned at opposite sides of the conventional printer. Each of the support ears respectively has a stepped shape for receiving different diameters of the support cores of the medium rolls. The stepped support ears of most conventional printers normally have at least two or three steps, but four-step support ears could also be found frequently.
Alternatively, the medium holding mechanism of a conventional printer may include a medium bar for supporting the medium rolls. The medium bar is normally secured to the conventional printer at one end, leaving an opposite end of the medium bar open for inserting and removing the medium rolls on the medium bar. Similar to the above-mentioned support ears, the medium bar often has a stepped shape to receive the medium rolls with different core diameters.
The conventional printer also has a medium guide mechanism for guiding and/or aligning the medium strip through the printer. Typically, the medium guide mechanism has a pair of pathway guides respectively positioned at opposite sides of a guide shaft. The pathway guides are positioned in the printer to guide the medium strip before the medium strip could reach a print head of the printer, thereby they help align the medium strip with the print head to provide better printing qualities. Each of the pathway guides often has a thin slot to allow the medium strip to pass through and both of the pathway guides are movably coupled to the guide shaft. Furthermore, the pathway guides are often equally spaced apart at opposite sides from a midpoint of the guide shaft. To accommodate medium strips having different dimensions, the pathway guides are configured to move toward or away from the midpoint of the guide shaft with. equal distance. Ordinarily, this is accomplished by a wheel-controlled sliding arrangement, where a user may adjust the distance between the pathway guides by turning an adjusting wheel. As a result, the pathway guides would always center the medium strip when the medium strip passes through the pathway guides. Alternatively, only one of the pathway guides is movably coupled to the guide shaft, while the other pathway guide is secured to an end of the guide shaft. Consequently, such pair of the pathway guides operates only to guide the medium strip and does not provide any centering function.
The above-mentioned stepped feature of the medium holding mechanism of the conventional printer provides a convenient solution to accommodate medium rolls having different core diameters of their support tubes. This feature, however, only partially solves the problems of holding the printable medium rolls having different core diameters. Particularly, a typical conventional printer has two or three steps on each support ear. As a result, only those medium rolls having core diameters fitted to these two or three steps will be held properly in the printer. Other medium rolls having different core diameter sizes will be, at best, loosely supported by the support ears. A loose medium roll mounted in the printer would potentially cause many problems during operation, such as the misalignment of the medium strip in the printer or the jamming of the printer due to uneven moving speed of the medium strip.
To reduce the loose-medium-roll problem, more, steps will have to be provided by the support ears. This arrangement would inevitably increase the overall width of the conventional printer due to the stepped feature of the support ears. As can be seen in FIG. 1, a conventional medium holding mechanism of a printer normally has two or more steps for each support ear (at least one step for each support ear is required). Each step of a support ear will need at least a certain amount of depth, e.g., 5 mm, on its rim in order to securely support the medium rolls. As a result, the overall width of the conventional medium holding mechanism will be increased by 2xc3x97D for each additional step of the support ear, where D is the depth of each step (supposed each step has the same depth D). The more steps adopted for each support ear, the wider medium holding mechanism, and thus the printer, is required. Furthermore, even though more steps may be able to fit more types of medium rolls, no conventional printer has an adjustable medium holding mechanism to fit many commercially available medium rolls with different core diameter sizes of their support tubes.
Another common problem to the conventional printer relates to the alignment of the medium strip between the medium guide mechanism and the medium holding mechanism. The medium guide mechanism in the conventional printer is separated and operated independently from the printer""s medium holding mechanism. Ordinarily, the medium guide mechanism is located close to a front end of the printer, where the print head is located, while the medium holding mechanism is located close to a back end of the printer. After mounted on the medium holding mechanism, the medium strip of the medium roll is pulled forward and inserted through the slots of the pathway guides of the medium guide mechanism. Thereafter, the medium strip is threaded through between a platen and the print head, where the platen rotatably presses the medium strip tightly against the print head to move the medium strip forward for printing. As mentioned, at least one of the pathway guides is usually controlled by a wheel to adjust their relative positions. The wheel is coupled to the guide shaft and is positioned at one side of the printer near the front end. In the conventional printer, the adjusting wheel operates independently from the medium holding mechanism and is adapted to be manually, controlled.
Since the medium guide mechanism and the medium holding mechanism of the conventional printer are separately adjusted and operated independently from each other, misalignment problems, thus, often occur to the medium strip when it moves from the medium holding mechanism to the medium guide mechanism of the printer. For example, when mounting the medium roll in the printer, the user will have to adjust the pathway guides and/or the support ears to accommodate the newly installed medium roll. Moreover, the misalignment problems will be further deteriorated if the medium rolls are loosely mounted on the support ears. Since the pathway guides and the support ears are adjusted independently, the medium strip might not be precisely aligned between the support ears of the medium holding mechanism and the pathway guides of the medium guide mechanism. Even a slight misalignment of the medium strip between these two mechanisms might cause many potential problems to the conventional printer. The problems include, inter alia, the twisting of the medium strip, which may cause bad printing quality to the medium strip, or it may jam the conventional printer. An improved holding and guiding mechanism of the printer is, therefore, needed to resolve the above-mentioned problems.
An object of the present invention is to provide an improved holding mechanism to a printer for properly holding medium rolls having different core dimensions of their support tubes. Another object of the present invention is to provide an integrated, medium guiding mechanism for better aligning the medium strip of the medium roll mounted on the printer. These objects are met by providing an adjustable core support mechanism and an integrated medium holding and medium guiding device to a printer respectively according to the present invention, as indicated in the claims appended hereto.
In one embodiment of the present invention, the present invention comprises a medium holding mechanism having an adjustable core support ear for receiving medium rolls having different core dimensions. In another embodiment, the present invention comprises an integrated medium holding and medium guiding device. The integrated medium device includes a medium holding mechanism and a medium guiding mechanism integrally coupled to the medium holding mechanism forcing the medium guiding mechanism to remain aligned with the medium holding mechanism. In addition, the medium holding mechanism is adjustable of its width to hold medium rolls of different lengths.
In a preferred embodiment, the integrated medium device according to the present invention has a pair of side support members respectively positioned at opposite ends of the integrated medium device. The side support members are coupled to each other through a connecting gear mechanism. The connecting gear mechanism comprises a gear set meshing to a pair of tooth rails for moving both side support members away or toward each other. Each of the side support members respectively comprises an adjustable core support ear, a guiding rail, and a guiding wall, preferably integrated with a respective side support member. Moreover, each of the adjustable core support ears has an upper semi-circular half and a lower semi-circular half, wherein the lower semi-circular half is adapted to be adjusted vertically for supporting medium rolls having different core dimensions of their support tubes. Since the core support ear, the guide rail, and the guide wall are integrated. with respective side support members, the medium strip will remain aligned when it moves from the medium roll, which is mounted on the adjustable core support ears, to a pair of guide caps respectively positioned over, the top of the guide rails at the front end of each side support member.
The foregoing and other objects, features and advantages of the invention will be apparent from the more particular description of preferred embodiments of the present invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.